Developers for thermal recording materials and thermal recording materials

ABSTRACT

The object of the present invention is to provide a novel developer capable or realizing a thermal recording material superior in preservation stability (i.e., heat resistance, moisture resistance) of color images and non-image areas, while satisfying the recent request for high sensitivity, and a thermal recording material using the developer. 
 
The developer for a thermal recording material of the present invention is characterized in that it consists of a composition containing, of condensates represented by the formula (I):  
                 
wherein R is a halogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, a cyano group, a nitro group, an aryl group or an aralkyl group, R in the number of m may be the same or different and m is an integer of 0-3, and n is an integer of 0-3, a condensate having two cores wherein n=0 as a main component, and at least one kind of condensate of the formula wherein n=1-3, and that a thermal recording material obtained using this developer shows high sensitivity, high dynamic color density, and superior preservation stability.

TECHNICAL FIELD

The present invention relates to a developer for thermal recordingmaterial and a thermal recording material.

BACKGROUND ART

In general, a thermal recording material (medium for thermal recording)is obtained by applying a coating liquid onto a support such as paper,plastic film and the like to form a heat coloring layer, wherein thecoating liquid is obtained by grinding and dispersing a basic dye, whichis colorless or in a pale color at ambient temperature, and an organicdeveloper, to give respective fine particles, mixing them and adding abinder, a filler, a sensitizer, a lubricant, other additive and the liketo the mixture. By heating with a thermal head, a thermal pen, a laserlight and the like, it affords a developed color record. The basicprinciple of such recording method is considered to be the change of thedye to have a color upon chemical contact of an electron donative dyewith an organic developer. Such recording method (thermal recordingmethod) is characterized in that it is free of the need of complicatedtreatments such as development, fixing and the like, it can record in ashort time using a comparatively economical and simple apparatus, ismaintenance free, is free of noise during recording, and the obtainedcolor is very clear, as compared to other recording methodsconventionally put to practical use, and has been widely used as arecording material for computer output, printer of electronic calculatorand the like, recorder for medical measurement, facsimile, automaticticket vending machine, label fields, copying machine and the like. Asmulti-purpose and high performance types of these apparatuses have beenprogressively provided in recent years, a higher-grade thermal recordingmaterial (medium for thermal recording) has been demanded. For highspeed recording and miniaturization of apparatuses, for example, thethermal energy of the thermal head of recording apparatuses tends tobecome very small, and a thermal recording material (medium for thermalrecording) to be used therefor is required to show sufficient colordensity to afford a high density and clear color image even with a verylittle energy.

To meet such request, various compounds having phenolic hydroxyl grouphave been proposed as a developer to be contained in a heat coloringlayer, and disclosed in, for example, JP-B-40-9309, JP-B-43-4160,JP-B-45-14039, JP-B-51-29830, JP-A-56-144193 and the like. Generally,bisphenol compounds, 4-hydroxybenzoic acid ester and the like have beenput to practical use alone or in combination of several kinds thereof.However, the conventional materials such as these are associated withproblems of, for example, low thermal response, insufficient colordensity achieved by high speed recording, inconsistent color densities,time-course changes in the density of color image after recording,discoloration during preservation, degraded heat resistance ofbackground, precipitation of white powder on a surface, which is what iscalled blooming, degraded re-printability and the like.

There has also been disclosed recently a method using a trisphenolcompound as a developer or an antifading agent in JP-A-9-278695,JP-A-2001-96926 and the like, but the use of such compound does not leadto a sufficient color density. While JP-A-58-181686 discloses a methodusing 2,2′-methylenediphenol compound as a developer, the methoddescribed in this publication is insufficient in sensitivity and imagestability, such as heat resistance, moisture resistance, weatherresistance and the like.

It is also known to add a novolac resin to a color layer of a thermalrecording material, but this is associated with a problem thatsufficient sensitivity cannot be obtained.

As mentioned above, a thermal recording material having preservationstability as mentioned above, such as heat resistance and moistureresistance, which satisfies recent requirements for high sensitivity,has not been obtained yet.

In view of the above-mentioned situation, the present invention aims atproviding a novel developer capable of realizing a thermal recordingmaterial superior in preservation stability (i.e., heat resistance,moisture resistance) of color image and non-image area, which satisfiesrecent requirements for high sensitivity, and a thermal recordingmaterial using the same.

DISCLOSURE OF THE INVENTION

As a result of intensive studies in an attempt to solve theabove-mentioned problems, the present inventors have found that acomposition containing a condensate having two cores of particularsubstituted phenols and formaldehyde as a main component, andcondensate(s) having 3 or more cores (e.g., condensate having 3 cores,or condensate having 3 cores and condensate having 4 cores, orcondensates having 3 to 5 cores) affords an extremely superior effect inimproving the sensitivity of a thermal recording material, and in thepreservation stability, which resulted in the completion of the presentinvention.

Accordingly, the present invention relates to (1) a developer for athermal recording material comprising a composition comprising, ofcondensates represented by the formula (I):

wherein

-   R is a halogen atom, a hydroxyl group, an alkyl group having 1 to 5    carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, a cyano    group, a nitro group, an aryl group or an aralkyl group,-   R in the number of m    -   may be the same or different and m is an integer of 0-3, and-   n is an integer of 0-3,-   a condensate having two cores wherein n=0 as a main component, and    at least one kind of condensate of the formula wherein n=1-3,-   (2) the developer for the thermal recording material of the    above-mentioned (1), wherein the condensate having two cores wherein    n=0 is contained in a proportion of 40-98%,-   (3) the developer for the thermal recording material of the    above-mentioned (1) or (2), wherein the condensate has a halogen    atom, a hydroxyl group, a lower alkyl group having 1 to 5 carbon    atoms, an alkoxyl group having 1 to 5 carbon atoms, a cyano group, a    nitro group, an aryl group or an aralkyl group at the p-position of    a hydroxyl group of a phenol group, and-   (4) a thermal recording material comprising a support and a    heat-coloring layer formed thereon, which layer comprises the    developer of any of the above-mentioned (1)-(3) and a basic dye.

The present invention is explained in detail in the following.

In the aforementioned formula (I), n is an integer of 0-3. m is aninteger of 0-3, preferably 1-3, more preferably 1. When m is 2 or 3, Rin the number of m may be the same or different. When m is 1-3, R ispreferably bonded to the m-position or p-position of hydroxyl group ofphenol group, more preferably the p-position of hydroxyl group of phenolgroup.

The R in the number of m each shows halogen atom, hydroxyl group, alkylgroup having 1 to 5 carbon atoms, alkoxyl group having 1 to 5 carbonatoms, cyano group, nitro group, aryl group or aralkyl group, preferablyalkyl group having 1 to 5 carbon atoms or aralkyl group.

The halogen atom is exemplified by chlorine atom, bromine atom andfluorine atom, and is preferably chlorine atom. The alkyl group having 1to 5 carbon atoms is exemplified by methyl, ethyl, propyl, isopropyl,t-butyl and t-amyl, preferably methyl, isopropyl and t-butyl. Thealkoxyl group having 1 to 5 carbon atoms preferably has 1 to 4 carbonatoms. The alkoxyl group having 1 to 4 carbon atoms is exemplified bymethoxy, ethoxy, propoxy, isopropoxy, butoxy and t-butoxy, and ispreferably methoxy. The aryl group is exemplified by phenyl, tolyl andnaphthyl, and is preferably phenyl. The aralkyl group is exemplified bycumyl and α-methylbenzyl.

The condensate having two cores, which is represented by the formula (I)(i.e., condensate of the formula wherein n=0), is concretely exemplifiedby

-   2,2′-methylenebisphenol,-   2,2′-methylenebis(4-chlorophenol),-   2,2′-methylenebis(5-chlorophenol),-   2,2′-methylenebis(4-hydroxyphenol),-   2,2′-methylenebis(5-hydroxyphenol),-   2,2′-methylenebis(4-methylphenol),-   2,2′-methylenebis(5-methylphenol),-   2,2′-methylenebis(4-ethylphenol),-   2,2′-methylenebis(5-ethylphenol),-   2,2′-methylenebis(4-propylphenol),-   2,2′-methylenebis(4-isopropylphenol),-   2,2′-methylenebis(5-isopropylphenol),-   2,2′-methylenebis(4-t-butylphenol),-   2,2′-methylenebis(5-t-butylphenol),-   2,2′-methylenebis(4-t-amylphenol),-   2,2′-methylenebis(4-methoxyphenol),-   2,2′-methylenebis(5-methoxyphenol),-   2,2′-methylenebis(4-cyanophenol),-   2,2′-methylenebis(5-cyanophenol),-   2,2′-methylenebis(4-nitrophenol),-   2,2′-methylenebis(5-nitrophenol),-   2,2′-methylenebis(4-phenylphenol),-   2,2′-methylenebis(5-phenylphenol),-   2,2′-methylenebis(4-cumylphenol) and-   2,2′-methylenebis[4-(α-methylbenzyl)phenol].

Of these, 2,2′-methylenebis(4-methylphenol),2,2′-methylenebis(4-ethylphenol), 2,2′-methylenebis(4-isopropylphenol),2,2′-methylenebis(4-t-butylphenol) and 2,2′-methylenebis(4-cumylphenol)are preferable, and 2,2′-methylenebis(4-t-butylphenol) and2,2′-methylenebis(4-cumyl phenol) are particularly preferable.

Examples of the condensates having 3 to 5 cores, which are representedby the formula (I) (i.e., condensates of the formula wherein n=1-3),include compounds corresponding to the compounds exemplified for theaforementioned condensate having two cores.

The content of the condensate having two cores in the developer(composition) for thermal recording material of the present invention ispreferably 40-98%, more preferably 40-90%, particularly preferably50-85%, of the entire developer (composition). When the content of thecondensate having two cores in the developer is less than 40%, orexceeds 98%, the objective effect of improving the sensitivity of athermal recording material and preservation stability of color image andnon-image area becomes difficult to express sufficiently. The developerfor thermal recording material of the present invention can be producedby a known synthetic method comprising, for example, reactingsubstituted phenol represented by the formula (II):

wherein R and m are as defined above, with formaldehyde in the presenceof an acid catalyst (e.g., hydrochloric acid, p-toluenesulfonic acid andthe like), and the like. The reaction is carried out in a suitableorganic solvent inert to the reaction, which can dissolve the startingmaterial and reaction product, such as water, methanol, ethanol,n-propyl alcohol, isopropyl alcohol, acetonitrile, toluene, chloroform,diethyl ether, N,N-dimethylacetamide, benzene, chlorobenzene,dichlorobenzene, diethyl ketone, ethyl methyl ketone, acetone,tetrahydrofuran and the like, at a reaction temperature of 0-150° C. forseveral hours to several dozen hours. The objective condensationcomposition thus obtained may contain a condensate of the formula (I)wherein n=not less than 4 as an impurity.

Specific examples of the substituted phenols represented by the formula(II) include phenol, p-chlorophenol, m-chlorophenol, o-chlorophenol,catechol, resorcinol, hydroquinone, p-cresol, m-cresol, o-cresol,p-ethylphenol, m-ethylphenol, o-ethylphenol, p-propylphenol,o-propylphenol, p-isopropylphenol, m-isopropylphenol, o-isopropylphenol,p-t-butylphenol, m-t-butylphenol, o-t-butylphenol, p-t-amylphenol,p-methoxyphenol, m-methoxyphenol, o-methoxyphenol, p-cyanophenol,m-cyanophenol, o-cyanophenol, p-nitrophenol, m-nitrophenol,o-nitrophenol, p-phenylphenol, m-phenylphenol, o-phenylphenol,p-cumylphenol, p-(α-methylbenzyl)phenol, 0-α-methylbenzyl)phenol and thelike.

The thermal recording material (medium for thermal recording) of thepresent invention is constituted by forming a heat coloring layercontaining the aforementioned developer of the present invention and abasic dye on a support.

In the thermal recording material of the present invention, the basicdye to be contained in the heat coloring layer may be any colorless topale color basic dye known in the field of pressure sensitive or thermalrecording paper and is not particularly limited. It is preferably aleucodye such as triphenylmethane, fluoran, fluorene, divinyl leucodyesand the like, particularly preferably fluoran leucodye, and mostpreferably anilinofluoran leucodye. The basic dye may be used alone orin combination of two or more kinds thereof.

Specific examples of the basic dye are shown in the following.

Triphenylmethane Leucodye

-   3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide-   3,3-bis(p-dimethylaminophenyl)phthalide    Fluoran Leucodye-   3-diethylamino-6-methylfluoran-   3-diethylamino-6-methyl-7-anilinofluoran-   3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran-   3-diethylamino-6-methyl-7-chlorofluoran-   3-diethylamino-6-methyl-7-(m-trifluoromethylanilino)fluoran-   3-diethylamino-6-methyl-7-(o-chloroanilino)fluoran-   3-diethylamino-6-methyl-7-(p-chloroanilino)fluoran-   3-diethylamino-6-methyl-7-(o-fluoroanilino)fluoran-   3-diethylamino-6-methyl-7-(m-methylanilino)fluoran-   3-diethylamino-6-chloro-7-methylfluoran-   3-diethylamino-6-chloro-7-anilinofluoran-   3-diethylamino-6-chloro-7-p-methylanilinofluoran-   3-diethylamino-7-methylfluoran-   3-diethylamino-7-chlorofluoran-   3-diethylamino-7-(m-trifluoromethylanilino)fluoran-   3-diethylamino-7-(o-chloroanilino)fluoran-   3-diethylamino-7-(p-chloroanilino)fluoran-   3-diethylamino-7-(o-fluoroanilino)fluoran-   3-diethylamino-benzo[a]fluoran-   3-diethylamino-benzo[c]fluoran-   3-dibutylamino-6-methylfluoran-   3-dibutylamino-6-methyl-7-anilinofluoran-   3-dibutylamino-6-methyl-7-(o,p-dimethylanilino)fluoran-   3-dibutylamino-6-methyl-7-(o-chloroanilino)fluoran-   3-dibutylamino-6-methyl-7-(p-chloroanilino)fluoran-   3-dibutylamino-6-methyl-7-(o-fluoroanilino)fluoran-   3-dibutylamino-6-methyl-7-(m-trifluoromethylanilino)fluoran-   3-dibutylamino-6-methyl-7-chlorofluoran-   3-dibutylamino-6-chloro-7-anilinofluoran-   3-dibutylamino-6-methyl-7-p-methylanilinofluoran-   3-dibutylamino-7-(o-chloroanilino)fluoran-   3-dibutylamino-7-(o-fluoroanilino)fluoran-   3-di-n-pentylamino-6-methyl-7-anilinofluoran-   3-di-n-pentylamino-6-methyl-7-(p-chloroanilino)fluoran-   3-di-n-pentylamino-7-(m-trifluoromethylanilino)fluoran-   3-di-n-pentylamino-6-chloro-7-anilinofluoran-   3-di-n-pentylamino-7-(p-chloroanilino)fluoran-   3-(N-ethyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran-   3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran-   3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran-   3-(N-ethyl-N-isoamylamino)-6-chloro-7-anilinofluoran-   3-(N-ethyl-N-tetrahydrofrufurylamino)-6-methyl-7-anilinofluoran-   3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran    Fluorene Leucodye-   3,6,6′-tris(dimethylamino)spiro[fluorene-9,3′-phthalide]-   3,6,6′-tris(diethylamino)spiro[fluorene-9,3′-phthalide]    Divinyl Leucodye-   3,3-bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrabromophthalide-   3,3-bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrachlorophthalide-   3,3-bis[1,1-bis(4-pyrrolidinophenyl)ethylen-2-yl]-4,5,6,7-tetrabromophthalide-   3,3-bis[1-(4-methoxyphenyl)-1-(4-pyrrolidinophenyl)ethylen-2-yl]-4,5,6,7-tetrachlorophthalide    Other Basic Dyes-   3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide-   3-(4-diethylamino-2-ethoxyphenyl)-3-(1-octyl-2-methylindol-3-yl)-4-azaphthalide-   3-(4-cyclohexylethylamino-2-methoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide-   3,3-bis(1-ethyl-2-methylindol-3-yl)phthalide-   3,6-bis(diethylamino)fluoran-γ-(3′-nitro) anilinolactam-   3,6-bis(diethylamino)fluoran-γ-(4′-nitro)anilinolactam-   1,1-bis[2′,2′,2″,2″-tetrakis-(p-dimethylaminophenyl)ethenyl]-2,2-dinitrile    ethane-   1,1-bis[2′,2′,2″,22″-tetrakis-(p-dimethylaminophenyl)ethenyl]-2-p-naphthoylethane-   1,1-bis[2′,2′,22″,2″-tetrakis-(p-dimethylaminophenyl)ethenyl]-2,2-diacetylethane-   bis[2,2,2′,2′-tetrakis-(p-dimethylaminophenyl)ethenyl]-methylmalonic    acid dimethyl ester

The heat coloring layer of the thermal recording material of the presentinvention may contain one or more conventionally known sensitizers tothe extent that the effect of the present invention is not impaired. Assuch sensitizer, for example, stearic acid amide, palmitic acid amide,methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide,N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acidamide, methylenebisstearic acid amide, methylolamide, N-methylol stearicacid amide, dibenzyl terephthalate, diocthyl terephthalate, diocthylterephthalate, benzyl p-benzyloxybenzoate, phenyl1-hydroxy-2-naphthoate, dibenzyl oxalate, di-p-methylbenzyl oxalate,oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, p-benzylbiphenyl, 4-biphenyl-p-tolyl ether, di(p-methoxyphenoxyethyl) ether,1,2-di(3-methylphenoxy)ethane, 1,2-di(4-methylphenoxy)ethane,1,2-di(4-methoxyphenoxy)ethane, 1,2-di(4-chlorophenoxy)ethane,1,2-diphenoxyethane, 1-(4-methoxyphenoxy)-2-(2-methylphenoxy)ethane,p-methylthiophenylbenzyl ether, 1,4-di(phenylthio)butane,p-acetotoluidide, p-acetophenetidide, N-acetoacetyl-p-toluidine,di(β-biphenylethoxy)benzene, p-di(vinyloxyethoxy)benzene,1-isopropylphenyl-2-phenylethane, 1,2-bis(phenoxymethyl)benzene,p-toluenesulfonamide, o-toluenesulfonamide, di-p-tolyl carbonate,phenyl-α-naphthyl carbonate, diphenylsulfone and the like can bementioned. Particularly, benzyl p-benzyloxybenzoate, stearic acid amide,ethylenebisstearic acid amide, di-p-methylbenzyl oxalate, oxalicdi-p-chlorobenzyl oxalate, 2-naphthylbenzyl ether, p-benzylbiphenyl,4-biphenyl-p-tolyl ether, 1,2-di(3-methylphenoxy)ethane,1,2-bis(phenoxymethyl)benzene and diphenylsulfone are preferable, and ofthese, when stearic acid amide, ethylenebisstearic acid amide, oxalicacid-di-p-methylbenzyl, di-p-chlorobenzyl oxalate, 2-naphthylbenzylether, p-benzyl biphenyl, 1,2-di(3-methylphenoxy)ethane,1,2-bis(phenoxymethyl)benzene and the like are used in combination witha condensation composition containing 2,2′-methylenebis(4-t-butylphenol)as a main component from among the developers of the present invention,more preferable results can be obtained.

The heat coloring layer may contain a conventionally known organicdeveloper to the extent that the effect of the present invention is notinhibited. Examples of such conventionally known developer include4-hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalicacid monoesters, bis(hydroxyphenyl)sulfides, 4-hydroxyphenylarylsulfones(e.g., 4-(4-propoxy-benzenesulfonyl)phenol,4-(4-isopropoxy-benzenesulfonyl)phenol and the like),4-hydroxyphenylarylsulfonates,1,3-di[2-(hydroxyphenyl)-2-propyl]benzenes, 4-hydroxybenzoyloxybenzoicacid esters, bisphenolsulfones and the like.

The production method of the thermal recording material of the presentinvention is not particularly limited, but generally, the developer ofthe present invention, a basic dye, and an additive such as a sensitizerand the like, which is added as necessary, are dispersed in a solutionof a binder or an emulsion of a binder or a dispersion containing abinder in paste therein to give a coating liquid, and the liquid isapplied to a support and dried to form a heat coloring layer.

Examples of the above-mentioned binder include completely saponifiedpolyvinyl alcohol having a polymerization degree of 200-1900, partiallysaponified polyvinyl alcohol, carboxy denatured polyvinyl alcohol, amidedenatured polyvinyl alcohol, sulfonic acid denatured polyvinyl alcohol,butyral denatured polyvinyl alcohol, other denatured polyvinyl alcohols,hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose,styrene-maleic anhydride copolymer, styrene-butadiene copolymer andcellulose derivatives such as ethyl cellulose and acetyl cellulose,polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acidester, polyvinylbutyral polystyrol and copolymers thereof, polyamideresin, silicone resin, petroleum resin, terpene resin, ketone resin,cumarone resin and the like. These polymers can be used alone or incombination of two or more kinds thereof according to the requestedquality. They may be dissolved in a solvent such as water, alcohol,ketone, ester, hydrocarbon and the like, or emulsified or dispersed inpaste in water or other medium and used.

In the present invention, the filler to be added to a heat coloringlayer is exemplified by inorganic or organic fillers such as silica,calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc,titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin,urea-formalin resin, styrene-methacrylic acid copolymer,styrene-butadiene copolymer, hollow plastic pigment and the like, andthe like.

Other than these, stabilizers such as p-nitrobenzoic acid metal salt(Ca, Zn), phthalic acid monobenzyl ester metal salt (Ca, Zn) and thelike, releasing agents such as fatty acid metal salt and the like,lubricants such as wax and the like, benzophenone or triazoleultraviolet absorbents, water resistant additives such as glyoxal andthe like, dispersing agents, antifoaming agents and the like can beadded as necessary.

In the present invention, the kind and amount of use of each materialsuch as basic dye, developer, sensitizer, binder, loading material andthe like to be used for the heat coloring layer are determined asappropriate depending on various performances that a heat coloring layeris requested to show, and are not particularly limited. In a mostgeneral example, about 1-8 parts by weight of a developer and 1-20 partsby weight of a filler, when it is to be added, are added suitably per 1part by weight of a basic dye. When a sensitizer is to be added, thesensitizer is added suitably in an amount of 0.1-2 parts by weight per 1part by weight of a developer, and a binder is added suitably in anamount of about 10-25 wt % of the entire solid content.

When a thermal recording material is to be produced according to thismethod, the basic dye and the developer, and the additives to be addedwhere necessary are preferably used after atomization in a grindingmachine such as a ball mill, an attriter, a sand grinder and the like orin a suitable emulsification apparatus to a particle size of not morethan several microns before use.

As a support on which to form a heat coloring layer, paper, recycledpaper, synthetic paper, plastic film, foamed plastic film, nonwovenfabric, metal foil and the like can be used, and a composite sheetcombining these can be also used.

In the thermal recording material of the present invention, moreover,preservability can be enhanced by forming an overcoating layer made of apolymer containing an organic loading material, and the like on the heatcoloring layer. Moreover, preservability and sensitivity can be enhancedby forming an undercoating layer containing an organic and/or aninorganic loading material under the heat coloring layer.

EXAMPLES

The present invention is explained in detail by referring to Examples,which are not to be construed as limitative. In the explanation, “part”means “part by weight”.

The composition ratio of the 2,2′-methylenebis(4-methylphenol) 80%condensation composition product described below is as follows.

-   2,2′-methylenebis(4-methylphenol):2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol:2,2′-methylenebis[6-[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol]=81:18:1

The composition ratio of the 2,2′-methylenebis(4-isopropylphenol) 60%condensation composition product is as follows.

-   2,2′-methylenebis(4-isopropylphenol):2,6-bis(2-hydroxy-5-isopropylbenzyl)-4-isopropylphenol:2,2′-methylenebis[6-[(2-hydroxy-5-isopropylphenyl)methyl]-4-isopropylphenol]=59:37:4

The composition ratio of the 2,2′-methylenebis(4-t-butylphenol) 40%condensation composition product is as follows.

-   2,2′-methylenebis(4-t-butylphenol):2,6-bis(2-hydroxy-5-t-butylbenzyl)-4-t-butylphenol:2,2′-methylenebis[6-(2-hydroxy-5-t-butylphenyl)methyl]-4-t-butylphenol:2,6-bis[[2-hydroxy-3-[(2-hydroxy-5-t-butylphenyl)methyl]-5-t-butylphenyl]methyl]-4-t-butylphenol=40:32:19:9

The composition ratio of the 2,2′-methylenebis(4-t-butylphenol) 55%condensation composition product is as follows.

-   2,2′-methylenebis(4-t-butylphenol):2,6-bis(2-hydroxy-5-t-butylbenzyl)-4-t-butylphenol:2,2′-methylenebis[6-[(2-hydroxy-5-t-butylphenyl)methyl]-4-t-butylphenol]:2,6-bis[[2-hydroxy-3-[(2-hydroxy-5-t-butylphenyl)methyl]-5-t-butylphenyl]methyl]-4-t-butylphenol=55:32:10:3

The composition ratio of the 2,2′-methylenebis(4-t-butylphenol) 70%condensation composition product is as follows.

-   2,2′-methylenebis(4-t-butylphenol):2,6-bis(2-hydroxy-5-t-butylbenzyl)-4-t-butylphenol:2,2′-methylenebis[6-[(2-hydroxy-5-t-butylphenyl)methyl]-4-t-butylphenol]=72:27:1

The composition ratio of the 2,2′-methylenebis(4-t-butylphenol) 80%condensation composition product is as follows.

-   2,2′-methylenebis(4-t-butylphenol):2,6-bis(2-hydroxy-5-t-butylbenzyl)-4-t-butylphenol:2,2′-methylenebis[6-[(2-hydroxy-5-t-butylphenyl)methyl]-4-t-butylphenol]=79:18:3

The composition ratio of the 2,2′-methylenebis(4-t-butylphenol) 90%condensation composition product is as follows.

-   2,2′-methylenebis(4-t-butylphenol):2,6-bis(2-hydroxy-5-t-butylbenzyl)-4-t-butylphenol=92:8

The composition ratio of the 2,2′-methylenebis(4-cumylphenol) 60%condensation composition product is as follows.

-   2,2′-methylenebis(4-cumylphenol):2,6-bis(2-hydroxy-5-cumylbenzyl)-4-cumylphenol:2,2′-methylenebis[(2-hydroxy-5-cumylphenyl)methyl]-4-cumylphenol:2,6-bis[[2-hydroxy-3-[(2-hydroxy-5-cumylphenyl)methyl]-5-cumylphenyl]methyl]-4-cumylphenol=60:26:10:4

Example 1

Liquid A (developer dispersion) condensation composition containing 80%of 2,2′-  6.0 parts methylenebis(4-methylphenol) 10% aqueous polyvinylalcohol solution 18.8 parts water 11.2 parts Liquid B (sensitizerdispersion) diphenylsulfone  4.0 parts 10% aqueous polyvinyl alcoholsolution 12.5 parts water  7.5 parts Liquid C (dye dispersion)3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran  2.0 parts 10%aqueous polyvinyl alcohol solution  4.6 parts water  2.6 parts

The above-mentioned Liquid A, Liquid B and Liquid C were ground in asand grinder to an average particle size of 1 micron. The dispersionswere mixed at the following ratio to give a coating liquid. Liquid A(developer dispersion) 36.0 parts Liquid B (sensitizer dispersion) 24.0parts Liquid C (dye dispersion)  9.2 parts Kaolin clay (50% dispersion)12.0 parts

The above-mentioned coating liquid was applied to one side of a basicpaper having a basic weight of 50 g/m² in a coating amount of 6.0 g/m²and dried at room temperature for 24 hr. This sheet was treated with asupercalender to smoothness of 500-600 sec to give a thermal recordingmaterial. The coated amount here means the amount of the solid adheredto the support after drying.

Example 2

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-isopropylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 3

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-isopropylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 4

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-isopropylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 5

In the same manner as in Example 1 except that a condensationcomposition containing 40% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 6

In the same manner as in Example 1 except that a condensationcomposition containing 40% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 7

In the same manner as in Example 1 except that a condensationcomposition containing 40% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 8

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 9

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 10

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 11

In the same manner as in Example 1 except that a condensationcomposition containing 70% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 12

In the same manner as in Example 1 except that a condensationcomposition containing 70% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 13

In the same manner as in Example 1 except that a condensationcomposition containing 70% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 14

In the same manner as in Example 1 except that a condensationcomposition containing 80% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 15

In the same manner as in Example 1 except that a condensationcomposition containing 80% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 16

In the same manner as in Example 1 except that a condensationcomposition containing 80% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 17

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 18

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 19

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 20

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-cumylphenol) was usedinstead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Example 21

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-cumylphenol) was usedinstead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

Example 22

In the same manner as in Example 1 except that a condensationcomposition containing 60% of 2,2′-methylenebis(4-cumylphenol) was usedinstead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 4-biphenyl-p-tolyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 23

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and stearic acid amide was used instead of diphenylsulfoneused for Liquid B (sensitizer dispersion), a thermal recording materialwas prepared.

Example 24

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and ethylenebisstearic acid amide was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 25

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 2-naphthylbenzyl ether was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 26

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and di-p-methylbenzyl oxalate was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 27

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and di-p-chlorobenzyl oxalate was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 28

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and p-benzyl biphenyl was used instead of diphenylsulfoneused for Liquid B (sensitizer dispersion), a thermal recording materialwas prepared.

Example 29

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 1,2-di(3-methylphenoxy)ethane was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 30

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 1,2-diphenoxyethane was used instead of diphenylsulfoneused for Liquid B (sensitizer dispersion), a thermal recording materialwas prepared.

Example 31

In the same manner as in Example 1 except that a condensationcomposition containing 90% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and 1,2-bis(phenoxymethyl)benzene was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion), a thermalrecording material was prepared.

Example 32

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), 1,2-di(3-methylphenoxy)ethane was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and3-di-n-pentylamino-6-methyl-7-anilinofluoran was used instead of3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used for Liquid C(dye dispersion), a thermal recording material was prepared.

Example 33

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), di-p-methylbenzyl oxalate was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and3-di-n-butylamino-6-methyl-7-anilinofluoran was used instead of3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used for Liquid C(dye dispersion), a thermal recording material was prepared.

Example 34

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), 1,2-bis(phenoxymethyl)benzene was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and3-di-n-pentylamino-6-methyl-7-anilinofluoran was used instead of3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used for Liquid C(dye dispersion), a thermal recording material was prepared.

Example 35

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), 1,2-bis(phenoxymethyl)benzene was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and3-di-n-butylamino-6-methyl-7-anilinofluoran was used instead of3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used for Liquid C(dye dispersion), a thermal recording material was prepared.

Example 36

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), 1,2-bis(phenoxymethyl)benzene was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and a mixtureof 3-di-n-pentylamino-6-methyl-7-anilinofluoran (50 wt %) and3-di-n-butylamino-6-methyl-7-anilinofluoran (50 wt %) was used insteadof 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used for LiquidC (dye dispersion), a thermal recording material was prepared.

Example 37

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused-instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), 1,2-di(3-methylphenoxy)ethane was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and a mixtureof 3-di-n-butylamino-6-methyl-7-anilinofluoran (50 wt %) and3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran (50 wt %) was usedinstead of 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used forLiquid C (dye dispersion), a thermal recording material was prepared.

Example 38

In the same manner as in Example 1 except that a condensationcomposition containing 55% of 2,2′-methylenebis(4-t-butylphenol) wasused instead of the condensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), di-p-methylbenzyl oxalate was used instead ofdiphenylsulfone used for Liquid B (sensitizer dispersion) and a mixtureof 3-di-n-pentylamino-6-methyl-7-anilinofluoran (50 wt %) and3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran (50 wt %) was usedinstead of 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran used forLiquid C (dye dispersion), a thermal recording material was prepared.

Comparative Example 1

In the same manner as in Example 1 except that2,2′-methylenebis(4-isopurpylphenol) was used instead of thecondensation composition containing 80% of2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Comparative Example 2

In the same manner as in Example 1 except that2,2′-methylenebis(4-t-butylphenol) instead of a condensation compositioncontaining 80% of 2,2′-methylenebis(4-methyl phenol) used for Liquid A(developer dispersion) in Example 1 and diphenylsulfone of Liquid B(sensitizer dispersion) was not used, a thermal recording material wasprepared.

Comparative Example 3

In the same manner as in Example 1 except that phenol novolac resin(Phenolite TD2090) manufactured by DAINIPPON INK AND CHEMICALS,INCORPORATED was used instead of the condensation composition containing80% of 2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion) and diphenylsulfone of Liquid B (sensitizer dispersion) wasnot used, a thermal recording material was prepared.

Comparative Example 4

In the same manner as in Example 1 except that phenol novolac resin(Phenolite TD2090) manufactured by DAINIPPON INK AND CHEMICALS,INCORPORATED was used instead of the condensation composition containing80% of 2,2′-methylenebis(4-methylphenol) used for Liquid A (developerdispersion), a thermal recording material was prepared.

The thermal recording materials obtained in the above Examples andComparative Examples were tested for the following quality andperformance. The results are shown in Tables 1-6. In the Tables, thenumerals in the upper line show the density of the recorded area andthose in the lower line show the density of the non-image area.

(1) Thermal Recordability Test (Dynamic Color Density)

The prepared thermal recording materials were subjected to printingusing TH-PMD manufactured by Ohkura Electric Co., Ltd. (thermal printer,equipped with a thermal head manufactured by Kyocera Corporation) at animpression energy of 0.38 mj/dot. The image density of the recorded areawas measured with the Macbeth densitometer (RD-914, using Amber Filter).

(2) Preservation Stability Test

[Heat Resistance Test]

The thermal recording materials printed on in the thermal recordabilitytest were stood for 24 hr in a high temperature dry environment at atest temperature of 60° C., and the image densities of the recorded areaand the non-image area were measured with the Macbeth densitometer.

[Moisture Resistance Test]

The thermal recording materials printed on in the thermal recordabilitytest were stood for 24 hr in an environment of a test temperature 40° C.and 90% RH, and the image densities of the recorded area and thenon-image area were measured with the Macbeth densitometer. TABLE 1dynamic color heat moisture developer sensitizer density resistanceresistance Ex. 1 condensation diphenyl- recorded 1.35 1.00 1.15composition sulfone area containing 80% of non- 0.09 0.10 0.102,2′-methylenebis- image (4-methylphenol) area Ex. 2 condensation nonerecorded 1.18 0.99 1.01 composition area containing 60% of non- 0.080.10 0.09 2,2′-methylenebis- image (4-isopropylphenol) area Ex. 3condensation diphenyl- recorded 1.36 0.83 0.94 composition sulfone areacontaining 60% of non- 0.04 0.09 0.07 2,2′-methylenebis- image(4-isopropylphenol) area Ex. 4 condensation 4- recorded 1.40 0.80 1.02composition biphenyl- area containing 60% of p-tolyl non- 0.05 0.10 0.052,2′-methylenebis- ether image (4-isopropylphenol) area Ex. 5condensation none recorded 1.00 0.95 0.98 composition area containing40% of non- 0.05 0.08 0.07 2,2′-methylenebis- image (4-t-butylphenol)area Ex. 6 condensation diphenyl- recorded 1.11 1.02 1.16 compositionsulfone area containing 40% of non- 0.05 0.11 0.06 2,2′-methylenebis-image (4-t-butylphenol) area Ex. 7 condensation 4- recorded 1.23 1.011.01 composition biphenyl- area containing 40% of p-tolyl non- 0.04 0.080.04 2,2′-methylenebis- ether image (4-t-butylphenol) area Ex. 8condensation none recorded 1.01 0.93 0.98 composition area containing55% of non- 0.06 0.08 0.09 2,2′-methylenebis- image (4-t-butylphenol)area Ex. 9 condensation diphenyl- recorded 1.21 1.10 1.21 compositionsulfone area containing 55% of non- 0.06 0.08 0.07 2,2′-methylenebis-image (4-t-butylphenol) area Ex. 10 condensation 4- recorded 1.36 1.121.24 composition biphenyl- area containing 55% of p-tolyl non- 0.06 0.080.06 2,2′-methylenebis- ether image (4-t-butylphenol) area Ex. 11condensation none recorded 1.20 1.00 1.10 composition area containing70% of non- 0.09 0.11 0.11 2,2′-methylenebis- image (4-t-butylphenol)area

TABLE 2 dynamic color heat moisture developer sensitizer densityresistance resistance Ex. 12 condensation diphenyl- recorded 1.31 1.071.11 composition sulfone area containing 70% of non- 0.04 0.06 0.042,2′-methylenebis- image (4-t-butylphenol) area Ex. 13 condensation4-biphenyl- recorded 1.33 1.02 1.03 composition p-tolyl area containing70% of ether non- 0.05 0.05 0.04 2,2′-methylenebis- image(4-t-butylphenol) area Ex. 14 condensation none recorded 1.15 0.99 1.00composition area containing 80% of non- 0.08 0.09 0.082,2′-methylenebis- image (4-t-butylphenol) area Ex. 15 condensationdiphenyl- recorded 1.36 1.04 1.27 composition sulfone area containing80% of non- 0.10 0.11 0.10 2,2′-methylenebis- image (4-t-butylphenol)area Ex. 16 condensation 4-biphenyl- recorded 1.36 0.95 1.25 compositionp-tolyl area containing 80% of ether non- 0.10 0.10 0.102,2′-methylenebis- image (4-t-butylphenol) area Ex. 17 condensation nonerecorded 1.10 0.97 1.01 composition area containing 90% of non- 0.090.11 0.11 2,2′-methylenebis- image (4-t-butylphenol) area Ex. 18condensation diphenyl- recorded 1.36 0.81 1.10 composition sulfone areacontaining 90% of non- 0.08 0.09 0.09 2,2′-methylenebis- image(4-t-butylphenol) area Ex. 19 condensation 4-biphenyl- recorded 1.390.80 1.10 composition p-tolyl area containing 90% of ether non- 0.080.10 0.09 2,2′-methylenebis- image (4-t-butylphenol) area Ex. 20condensation none recorded 1.00 0.98 0.95 composition area containing60% of non- 0.06 0.07 0.06 2,2′-methylenebis- image (4-cumylphenol) areaEx. 21 condensation diphenyl- recorded 1.13 1.07 1.13 compositionsulfone area containing 60% of non- 0.08 0.09 0.10 2,2′-methylenebis-image (4-cumylphenol) area Ex. 22 condensation 4-biphenyl recorded 1.281.13 1.27 composition p-tolyl area containing 60% of ether non- 0.070.10 0.11 2,2′-methylenebis- image (4-cumylphenol) area

TABLE 3 dynamic color heat moisture developer sensitizer densityresistance resistance Ex. 23 condensation stearic recorded 1.36 0.981.17 composition acid area containing 90% of amide non-image 0.08 0.080.10 2,2′-methylenebis- area (4-t-butylphenol) Ex. 24 condensationethylene recorded 1.32 1.02 1.13 composition bis- area containing 90% ofstearic non-image 0.08 0.09 0.09 2,2′-methylenebis- acid area(4-t-butylphenol) amide Ex. 25 condensation 2- recorded 1.37 1.07 1.15composition naphthyl area containing 90% of benzyl- non-image 0.07 0.090.10 2,2′-methylenebis- ether area (4-t-butylphenol) Ex. 26 condensationdi-p- recorded 1.43 1.10 1.09 composition methyl- area containing 90% ofbenzyl non-image 0.08 0.09 0.10 2,2′-methylenebis- oxalate area(4-t-butylphenol) Ex. 27 condensation di-p- recorded 1.40 1.18 1.15composition cholorobenzyl area containing 90% of oxalate non-image 0.080.09 0.10 2,2′-methylenebis- area (4-t-butylphenol) Ex. 28 condensationp- recorded 1.43 1.09 1.02 composition benzyl- area containing 90% ofbiphenyl non-image 0.08 0.09 0.09 2,2′-methylenebis- area(4-t-butylphenol) Ex. 29 condensation 1,2- recorded 1.45 1.16 1.13composition di(3- area containing 90% of methyl- non-image 0.08 0.090.09 2,2′-methylenebis- phenoxy) area (4-t-butylphenol) ethane Ex. 30condensation 1,2-di- recorded 1.42 1.18 1.10 composition phenoxy- areacontaining 90% of ethane non-image 0.08 0.09 0.09 2,2′-methylenebis-area (4-t-butylphenol) Ex. 31 condensation 1,2-bis- recorded 1.45 1.071.02 composition (phenoxy area containing 90% of methyl)- non-image 0.080.09 0.10 2,2′-methylenebis- benzene area (4-t-butylphenol)

TABLE 4 dynamic color heat moisture dye developer sensitizer densityresistance resistance Ex. 32 3-di-n- condensation 1,2-di- recorded 1.451.07 1.02 pentyl- composition (3- area amino-6- containing methyl- non-0.08 0.09 0.10 methyl-7- 55% of phenoxy) image anilino- 2,2′- ethanearea fluoran methylene- bis(4-t- butyl- phenol) Ex. 33 3-di-n-condensation di-p- recorded 1.42 1.09 1.06 butyl- composition methyl-area amino-6- containing benzyl non- 0.08 0.09 0.10 methyl-7- 55% ofoxalate image anilino- 2,2′- area fluoran methylene- bis(4-t- butyl-phenol) Ex. 34 3-di-n- condensation 1,2-bis- recorded 1.40 0.98 1.00pentyl- composition (phenoxy area amino-6- containing methyl)- non- 0.080.09 0.10 methyl-7- 55% of benzene image anilino- 2,2′- area fluoranmethylene- bis(4-t- butyl- phenol) Ex. 35 3-di-n- condensation 1,2-bis-recorded 1.42 1.07 1.02 butyl- composition (phenoxy area amino-6-containing methyl)- non- 0.08 0.09 0.10 methyl-7- 55% of benzene imageanilino- 2,2′- area fluoran methylene- bis(4-t- butyl- phenol) Ex. 363-di-n- condensation 1,2-bis- recorded 1.45 1.13 1.10 pentyl-composition (phenoxy area amino-6- containing methyl)- non- 0.08 0.110.10 methyl-7- 55% of benzene image anilino- 2,2′- area fluoran + 3-methylene- di-n- bis(4-t- butyl- butyl- amino-6- phenol) methyl-7-anilino- fluoran

TABLE 5 dynamic color heat moisture dye developer sensitizer densityresistance resistance Ex. 37 3-di-n- condensation 1,2-di- recorded 1.461.10 1.05 butyl- composition (3- area amino-6- containing methyl- non-0.08 0.10 0.10 methyl-7- 55% of phenoxy) image anilino- 2,2′- ethanearea fluoran + 3- methylene- (N- bis(4-t- ethyl-N- butyl- isoamyl-phenol) amino)-6- methyl-7- anilino fluoran Ex. 38 3-di-n- condensationdi-p- recorded 1.45 1.07 1.10 pentyl- composition methyl- area amino-6-containing benzyl non- 0.08 0.10 0.10 methyl-7- 55% of oxalate imageanilino- 2,2′- area fluoran + 3- methylene- (N- bis(4-t- ethyl-N- butyl-isoamyl- phenol) amino)-6- methyl-7- anilino- fluoran

TABLE 6 dynamic color heat moisture developer sensitizer densityresistance resistance Comp. 2,2′- none recorded 0.86 0.58 0.52 Ex. 1methylenebis(4- area isopropylphenol) non- 0.10 0.10 0.09 image areaComp. 2,2′- none recorded 0.77 0.52 0.58 Ex. 2 methylenebis(4-t- areabutylphenol) non- 0.09 0.10 0.10 image area Comp. phenol novolac nonerecorded 0.37 0.20 0.15 Ex. 3 resin area non- 0.08 0.08 0.11 image areaComp. phenol novolac di- recorded 0.58 0.41 0.77 Ex. 4 resin phenyl-area sulfone non- 0.08 0.08 0.12 image area

As shown in Tables 1-6, the thermal recording materials obtained usingthe developers (Examples 1-38) consisting of the composition of thepresent invention showed superior preservation stability whilemaintaining high dynamic color density. In contrast, when2,2′-methylenebis(4-isopropylphenol) or2,2′-methylenebis(4-t-butylphenol) alone was used as in ComparativeExamples 1 and 2, the dynamic color density was low and the preservationstability was poor. In addition, the phenol novolac resins having highpolymerization ratio as in Comparative Examples 3 and 4 showed very lowdynamic color density, thus failing to afford satisfactory performance.

Industrial Applicability

According to the present invention, a thermal recording material havinghigh sensitivity and high dynamic color density, and superior inpreservation stability can be obtained.

This application is based on patent application Nos. 2001-167233 and2001-301577 filed in Japan, the contents of which are herebyincorporated by reference.

1-8. (canceled)
 9. A developer for a thermal recording material, thedeveloper comprising a composition comprised of condensates representedby the formula (i):

wherein R is an alkyl group having 1 to 5 carbon atoms or cumyl group, nis an integer of 0-3, wherein said composition includes: (i) acondensate of the formula (I) having two cores wherein n=0 as a maincomponent, and (ii) at least one condensate of the formula (I) wherein nis an integer of 1-3.
 10. The developer for the thermal recordingmaterial of claim 9, wherein the condensate having two cores wherein n=0is contained in a proportion of 40-98%.
 11. The developer for thethermal recording material of claim 9, wherein the condensate having twocores wherein n=0 is contained in a proportion of 40-90%.
 12. A thermalrecording material comprising a support and a heat coloring layer formedthereon, which layer comprises the developer of claim 9 and a basic dye.13. A thermal recording material comprising a support and a heatcoloring layer formed thereon, which layer comprises the developer ofclaim 10 and a basic dye.
 14. A thermal recording material comprising asupport and a heat coloring layer formed thereon, which layer comprisesthe developer of claim 11 and a basic dye.